1. Field of the Present Invention
The invention relates to optical switches, and more specifically, to the switching of light, or electromagnetic radiation, by electronic means.
2. Background of the Present Invention
Fiber optic communication has become a significant means of providing high bandwidth for digital and other communications. Low-loss fiber optics together with high-speed modulation techniques make optical communications the preferred medium for modern communication systems.
In order to provide effective communications, altering, or switching, the optical paths of communication light beams must be provided. This allows sets of signals to be transmitted to the desired destinations as needed.
Currently, a preferred method of switching such light beams is by guiding such beams with mirrors which can be mechanically moved to change the transmitted path when needed. Typically, an array of micro-mechanical mirrors are provided on a substrate to form a chip, and electrostatic forces are used to rotate the mirrors physically. This requires very high voltages, typically in excess of 100 Volts, in order to provide sufficient force to rotate the mirrors. Furthermore, because the mirrors are capable of rotating by any arbitrary angle, sophisticated electronic controls are necessary to provide feedback in order to ensure that the proper angles are achieved and maintained during operation. Such high voltage power supplies, and the associated electronics needed to control the electrostatic voltages to the micro-mechanical mirror chips, are expensive, large, consume significant power, and are relatively unreliable.
Other methods of switching optical signals have been proposed which also present certain limitations. One method is to use liquid crystals, which can be modulated through application of an electric field, to change from partially transmitting light to partially reflecting light. Unfortunately, while such liquid crystals do provide low power operation, they are limited to reflecting only light of a particular polarization, and are also very slow, switching in the time scale of milliseconds. Another alternative method is to use a material which undergoes a transition to a superconducting state. In this method a material becomes highly reflective when superconducting, and becomes a lossy transmitter of light when not in its superconducting state. Unfortunately, such systems must be chilled to very low temperatures, and also are relatively slow to switch, since they are switched by heating or cooling them about the critical temperature, or by providing large magnetic fields to break the superconductivity. Furthermore, such superconducting materials are relatively poor transmitters of light when not in a superconducting state.
Thus, high speed switching of optical signals without the use of high voltages and/or sophisticated electronic controls, and at ambient temperatures is desired.